Ensure the code model receives file names with clean paths ('/')
and fix paths in the relevant places of the code model. Pass on clean
paths from Cpp reference find and display them correctly in the search
window tooltip.

Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>

Also fix focusing issues of the replace line edit.

Reviewed-by: Roberto Raggi

Unfortunately, the MacroResolver does not scale and we get pretty bad performances when parsing big projects.

Ensure the user can stop a semantic search and added a method to get a pointer to the ModelManagerInterface.

Also move Designer::Internal::FormWindowEditor ->
Designer::FormWindowEditor.